This proposal is part of the Collaborative Studies of the Psychobiology of the Depressive Illnesses, which are under the aegis of the Clinical Research Branch of the Division of Extramural Research Program of the NIMH. The purpose of the Collaborative Studies is to clarify the nosology of the depressive illnesses, examine the role of genetic factors in the development of depression, and explore the relationship between clinical, biological and psychophysiological variables. The present proposal is for a pilot and feasibility study of the larger Collaborative Studies of the Psychobiology of the Depressive Illnesses. Two hundred patients with affective disturbances will be evaluated at the five participating facilities using the battery of initial assessment procedures that will be used in the larger study. Data from this study will be analyzed in terms of the hypotheses of the larger study, the relationship between the assessment instruments, and the interjudge reliabilities of the clinical procedures. Prior to the pilot and feasibility study, further work will be done to develop methods for evaluating life events prior to the onset of the illness and for determining the presence of psychiatric illness in family members of the patient using family history and family study procedures.